1. Field of the Invention
The present invention relates to a system for and a method of analyzing the surface condition of a printed circuit board (PCB) using RGB colors and more particularly, a system for and a method of analyzing the surface condition of a PCB using RGB colors, in which the oxidation degree of the PCB is quantitatively measured, based on relative values of RGB signals, in unit pixels of an image obtained by picking up an image of the PCB.
2. Description of the Related Art
PCBs, which are mounted thereon with electronic elements such as semiconductor chips, resistors, and capacitors, serve to electrically connect the mounted electronic elements via conductive wiring patterns of desired shapes or to supply a drive voltage to the electronic elements. Such a PCB includes a board for mounting electronic elements thereon, and wirings of desired patterns for electrically connecting the mounted electronic elements.
The configuration of such a PCB and the procedure for manufacturing the PCB will now be described in detail. A copper clad laminate (CCL) is first prepared by forming a copper film on one surface or both surfaces of a thin substrate made of an insulating material such as epoxy or bakelite resin. In order to increase the bonding force of the copper film to the resin of the substrate, the formation of the copper film is carried out in such a manner that the copper film reacts with the resin of the substrate, thereby penetrating into the resin by a certain depth, for example, about 5 μm.
Thereafter, a shearing process is carried out so as to shear the CCL to have a desired panel size suitable for subsequent processes. The sheared CCL is then subjected to a beveling process, so that it has round corners. Subsequently, the CCL is subjected to a scrubbing process for removing fingerprints or dust on the copper film surface of the CCL or providing roughness to the copper film surface in order to increase the bonding force of a dry film to be laminated on the copper film surface in a subsequent lamination process.
After completion of the scrubbing process, the dry film is formed on the copper film surface. The dry film consists of a film-shaped photoresist adapted to form a desired wiring pattern on a PCB, a Mylar film for providing a certain degree of flexibility, and a cover film.
An artwork film formed with a wiring pattern is then attached to the dry film. Thereafter, the resulting structure is subjected to an exposure process in which ultraviolet rays are irradiated onto the structure so as to cure portions of the photoresist reacting with the ultraviolet rays. At this time, the other portions of the photoresist do not vary. A development process is then carried out using a certain developer, thereby dissolving and, thus, removing uncured portions of the photoresist while leaving the cured photoresist portion to be subsequently used as an etch resist. Thus, an etch mask made of the etch resist is formed on the copper film of the CCL for formation of a desired wiring pattern.
After formation of the etch mask, an etchant is sprayed onto the resulting structure, thereby removing an exposed portion of the copper film corresponding to a region other than a wiring pattern region where the copper film is protected by the etch resist. Accordingly, a desired wiring pattern is formed. After formation of the wiring pattern, the etch resist is completely stripped. Thus, the PCB is completed.
Such a PCB manufacturing method involves repeated processes of lamination, etching and cleaning of copper films, as described above. However, the final product, that is, the PCB, may have a poor surface condition due to contamination sources such as dust or fingerprints left on the copper films, and oxidation or discoloration of the wiring patterns.
In particular, where oxidation occurs at bonding pads of the PCB, made of a metal such as Cu, to be connected to corresponding portions of a semiconductor chip, attachment of balls or wires may not be achieved due to oxides present on the bonding pad surfaces. Although the attachment may be achieved, its bonding strength is considerably low.
Accordingly, it is necessary to measure the degree of an oxidation at the metal surface of a PCB enabling identification of the above mentioned problem. Conventionally, this measurement is achieved with the operator's naked eye or expensive equipment such as a surface analyzer.
However, the method of visually inspecting the surface condition of a PCB by the operator makes it difficult to obtain accurate inspection results because it is greatly influenced by various parameters of the surroundings such as the ability of the operator, surrounding brightness, and time. Furthermore, this method has limited repeatability and reproducibility for the inspection results. For this reason, there is a problem in that it is impossible to obtain quantitative data capable of determining respective qualities of optional PCBs.
On the other hand, where an expensive surface analyzer such as ESCA or Auger is used, it can accurately measure the condition of the metal surface of an optional PCB. However, there are problems in that the surface analyzer increases the manufacturing costs of PCBs due to high installation costs thereof, and cannot be easily applied to products newly developed.